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PRRS and Enzootic Pneumonia in 50 days old multi-source pigs: What measures are recommended to control the problem?

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PRRS and Enzootic Pneumonia in 50 days old multi-source pigs: What measures are recommended to control the problem?

PRRS and Enzootic Pneumonia in 50 days old multi-source pigs: What measures are recommended to control the problem?

Answered by: Enric Marco I Published on: May 15, 2017

Question:
A 900-Finishing unit with a deep bedding system is filled with 45-50 days old multi-source pigs. The animals have respiratory symptoms. Six serum samples were taken at animals at different age. Serological ELISA tests were performed for PRRS, Enzootic pneumonia, PCV2 and Influenza. Results were positive to PRRS (4/6) and Enzootic Pneumonia (3/6). What measures are recommended to control the problem?, should it be voided to introduce more animals?, should we implement any preventive medication? and can the animals be sent to market?

Answer:
Detection of PRRS positive serology in a finisher farm does not always mean that the problems are due to a PRRS virus infection.

There is a possibility that the animals have already overcome the disease and what we are detecting are the antibody titters that had developed against it. To know precisely, tests should be performed to detect the virus such as PCR tests in blood or oral fluids, and not its antibodies.

The fact of having positive and some negative results to serology is not an unusual finding as it is a quite common situation after coming in contact with the pathogen. We know that there is a percentage of animals that do not develop a positive serological reaction after contacting the pathogen and this percentage can vary, from farm to farm, reaching up to 10%.

If we also do not know the time of infection, the percentage of negative results may increase over time. The respiratory clinical signs observed are very likely to be caused by concomitant infections and in this case one of the pathogens that could be involved is Mycoplasma hyopneumoniae. In this case I would recommend to implement a medication with an effective antibiotic against Mycoplasma to control the infection and it would be best to stop the entry of new animals until controlling the clinical signs.

Once the clinical signs have been controlled and the antibiotic withdrawal period has been respected, the animals can be marketed without any problem. However, it seems this finishing unit is introducing animals from different farms and it is possible that the health status of those source farms is different. In such a case, it would be advisable to convince the suppliers to vaccinate the animals against PRRS and Mycoplasma at the source farm before sending them to the fattening unit.

If this is not an option, I would recommend emergency vaccination on arrival and trying to keep the newcomers as far as possible from the older animals to see if in this way the percentage of pigs developing respiratory clinical symptoms is reduced.